Combination type refrigerator

ABSTRACT

A combination type refrigerator having a freezing storage compartment provided with a heat exchanger and a cold storage compartment also provided with a heat exchanger, wherein a cooler is on-off controlled in response to the detection of a certain predetermined temperature in the cold storage compartment and the defrosting of the freezing storage compartment is effected by connecting both the heat exchangers in series and directly supplying pressurized hot gas to the heat exchanger for the freezing storage compartment. It is characterized by a heating means disposed in a suitable position within the cold storage compartment, and which heating means is capable of generating an amount of heat just sufficient to permit continuous operation of the cooler without causing any temperature rise in the cold storage compartment during the defrosting operation in the freezing storage compartment and is operated during the defrosting operation in the storage compartment.

United States Patent. [191 Nijo l l July 9,1974

[ COMBINATION TYPE REFRIGERATOR [75] Inventor: Kiyoichi Nijo, Osaka, Japan [73] Assignee: Naniwa Sangyo Kabushikigaisha,

Osaka-City, Japan [22] Filed: Aug. 1, 1972 [21] Appl. No.: 276,954

2/1954 Shoemaker ..62/l56 Primary Examiner-Meyer Perlin I Attorney, Agent, or Firm-Browdy and Neimark [57] ABSTRACT A combination type refrigerator having a freezing storage compartment provided with a heat exchanger and a cold storage compartment also provided with a heat exchanger, wherein a cooler is on-off controlled in response to the detection of a certain predetermined temperature in the cold storage compartment and the defrosting of the freezing storage compartment is effected by connecting both the heat exchangers in series and directly supplying pressurized hot gas to the heat exchanger for the freezing storage compartment. It is characterized by a heating means disposed in a suitable position within the cold storage compartment, and which heating'means is capable of generating an amount of heat just sufficient to permit continuous operation of the cooler without causing any temperature rise in the cold storage compartment during the defrosting operation in the freezing storage compartment and is operated during the defrosting operation in the storage compartment.

4 Claims, 7 Drawing Figures THERMOSTAT COMPRESSOR MOT OR PAIENTED 91974 v 3.822.564

' SHEET10F3 COMPRESSOR M O T O R FIG. 2

mamam 14 3.822564 SHEET 2 0F 3 F|G.3 FIG-4 FIG. 6

DEscRIPTION OF THE PRIOR ART on-off controlling a cooler in response to the temperature detection on the side of the cold storage compartment and the defrosting in the freezing storage compartment is effected by supplying pressurized hot gas directly to the heat exchanger for the freezing storage compartment.

In the refrigerator of this type, the temperature conlier, which uses a heating means capable of generating a substantially equal amount of heat tothat absorbed by the heat exchanger for the cold storage compartment, said heating means being disposed within the cold storage compartment or in the vicinity of the heat exchanger for the cold storage compartment and being operated at the time of defrosting the heat exchanger trol which is done to maintain a constant temperature in the cold storage compartment, is effective in maintaining not only the cold storage compartment but also the freezing storage compartment at respective constant temperatures, as is disclosed, for instance, in Japanese Patent Publication No. 45-21865/1970.

In such refrigerator, the defrosting on the side of the freezing storage is very important. When the heat exchanger is frosted, its cooling efficiency is extremely lowered. As an effective means or removing the frost formed on the heat exchanger, there is a so-called pressurized hot gas defrosting system, in which pressurized cooling medium is supplied not through condenser and expansion valve but directly to the freezing storage compartment heat exchanger for the defrosting thereof. However, in the refrigerator of the type mentioned above, in which the temperature control is done by on-off controlling the cooler in response to the temperature detection done on the side of the cold storage compartment, when the cold storage compartment is cooled down to a certain low temperature the operation of the cooler is stopped to cut the supply of the cooling medium. If the cooling medium supply is cut during the defrosting operation, the defrosting proceeding in the freezing storage compartment is interrupted since the supply of pressurized hot gas to the heat exchanger for the freezing storage compartment is cut off.

In case of a refrigerator where a timer is used for the defrosting operation, it is liable to happen that before the defrosting goesto completion the hot gas path is switched so that hot gas having been compressed, condensed and then gasified is supplied to the heat exchanger for the freezing storage compartment. In such case, the defrosting operation ends while the defrosting is still incomplete.

OBJECT OF THE INVENTION The invention has an object of providing a combination type refrigerator of the type mentioned earlier, which is capable of greatly reducing the time required for the defrosting in the freezing storage compartment and ensuring complete defrosting as well as eliminating the occurrence of the flood-back otherwise very likely to occur in this type of refrigerator to dispense with any particular flood-back preventive means.

SUMMARY OF THE INVENTION According to the invention there is provided a combination type refrigerator of the type mentioned earfor the freezing storage compartment. Thus, it is featured that the overcooling in the cold storage compartment due to the flow of condensed hot gas into the cold storage compartment heat exchanger as a result of defrosting of the heat exchanger for the freezing storage compartment heat exchanger is avoided, thereby to ensure continuous run of the cooler until the end of the defrosting operation. Also since the temperature of the cold storage compartment heat exchanger never becomes lower than 0C., this heat exchanger is never frosted, so there is no need of defrosting it.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of one embodiment of the invention.

FIG. 2 is a front elevational view, partly broken away, showing a heat exchanger for the cold storage compartment.

FIG. 3 is a side sectional view of the same.

FIG. 4 is a side view of an example of the frost detector.

FIG. 5 is a schematic showing of a defrosting system for carrying out defrosting on the side of the freezing storage compartment.

FIG. 6 is a sectional view of a temperature sensor.

FIG. 7 is a schematic representation of another embodiment of the invention.

FIG. 1 shows schematically a preferred embodiment of the combination type refrigerator according to the invention. Referring to the Figure, reference numeral 1 designates a compressor. In the normal operation, the cooling medium compressed by the compressor 1 is liquefied by a condenser 3 provided on a main path 2, and is circulated through an expansion valve 4 also provided in the. main path 2 into the combination refrigerator interior 6. The refrigerator 6 is divided into a freezing storage compartment 7 and a cold storage compartment 8. The heat exchanger 9 for the freezing storage compartment and the heat exchanger 10 for the cold storage compartment are connected in series. The cooling medium passing through the expansion valve 4 first enters the heat exchanger 9 for the freezing storage compartment. The cooling medium coming out of the heat exchanger 9 after cooling the freezing storage compartment, is circulated either through an electro operation. Namely, there is provided a by-pass-part l2 branching from a main path section between compressor l and condenser 3 and by-passing the condenser 3 and expansion valve 4. The by-pass 12 connects with the main path 2 at. a three-way valve 13. There is also provided another by-pass 14 by-passing the aforementioned electromagnetic valve 11 and connecting both the heat exchangers through an expansion valve therebetween. At the time of the defrosting operation, the three-way valve is changed over to the side of the by-pass 12 by the action of a solenoid 13a, while the electromagnetic valve 11 is closed by the action of a solenoid 11a. When this state sets in, the hot gas forced from the compressor 1, so long as the compressor 1 is operative, flows through the threeway valve 13, by-pass 12, heat exchanger 9 for freezing storage compartment, by-pass 14, expansion valve 15 and heat exchanger 10 for the cold storage compartment and returns to the compressor 1. Numeral 16 designates a heating means provided on the side of the cold storage compartment 8, to be described hereinafter in detail.

FIGS. 2 and 3 show the construction of the heat exchanger 10 for the cold storage compartment. It consists of a meandering cooling medium pipe 17 and many cooling fins l8 fitted on the cooling pipe 17, and it is accommodated in a housing 80 open at the bottom 81 and provided with an opening 82 formed on an upper wall portion. Disposed within the housing 80 and facing the opening 82 is a blast fan 18 for forced air fiow within the cold storage compartment 8. Provided under the heat exchanger 10 is the aforementioned heating means 16, for instance a resistance heater. In the present embodiment, the cooling of the cold storage compartment 8 is efiected as the air withdrawn into the heat exchanger housing 80 from the bottom opening 81 by the rotation of the blast fan 18 is cooled while rising within the housing 80 past the heat exchanger 80 and is blown out of the housing 80 through its openin 82 into the compartment 8. 1

The heater 16 is adapted to generate substantially the same amount of heat as the heat absorbed from the air within the cold storage compartment 8 by the heat exchanger 10. Thus, when the heater 16 is operating, even though the cooling medium flows past the heat exchanger 10 the cold storage compartment 8 remains neither cooled nor heated. The heater 16 is operated at the time of the defrosting operation carried out on the side of the freezing storage compartment 7, as will be described hereinafter in detail.

The temperature control system for the temperature control on the side of the cold storage compartment may be the one as employed in the usual refrigerator using a single temperature sensor for intermittently onoff controlling a cooler according to a temperature detected by the temperature sensor. Also, any wellknown temperature sensor may be used such as thermocouple and thermistor. Of course, temperature control of increased precision as may be achieved with a system using two temperature sensors as those invented by theinventors of the present invention and disclosed in the Japanese Patent Publication No. 45-21074/1970 is desirable. I

In the present embodiment, the frost detector provided on the side of the freezing storage compartment utilizes the fact that vibration such as that of the compressor under operation, vibrations generated in the cooling medium pipe as the cooling medium passes therethrough and vibrations due to the rotation of the fan are transmitted to the cooling fins to cause vibration thereof. More particularly, vibrations of a fin are adapted to be transmitted through frost or ice formed thereon to the frost detector, whereby the presence of frost or ice may be detected.

FIG. 4 shows an example of the frost detector used in the present embodiment. It comprises a well-known pick-up 43 serving as vibration detector, which consists of a detector body 44, a vibration sensing plate 45 made of a rust-proof metal, a vibration rod 46 connecting the body 44 and plate 45, and terminals 4715 and 48B. The pick-up body 44 is held free from vibration within the cold storage compartment 7 such that the vibration sensing plate 45 faces a cooling fin 49 at a predetermined distance 50. While vibrations such as those due to the rotation of the fan are always transmitted to the cooling fin 49, they are not transmitted to the pick-up 43 so long as the gap 50 is present. However, when the freezing storage compartment 7 being cooled reaches a certain low temperature, water vapor within the compartment, such as moisture given off the stored matter, becomes attached as frost or ice on the cooling fin 49, the frost or ice developing in the gap 50 between the fin 49 and vibration sensing plate 45. When this situation sets in, the vibrations transmitted to the fin 49 are also transmitted through the vibration sensing plate 45 to the pick-up 43. Thus, an electric output appears between the terminals 47E and 47E of the pick-up 43.

FIG. 5 shows a defrosting control circuit together with the heat exchanger 9 for the freezing storage compartment. In the Figure, numeral 51 designates a meandering cooling medium pipe 51 extending in the freezing storage compartment 7, and on the cooling pipe 51 are fitted many cooling fins 49. The cooling pipe 51 and cooling fins 49 constitute the heat exchanger 9 for the freezing storage compartment. A temperature sensor A is provided in close contact with a cooling fin 49 near the upstream end of the meandering cooling pipe 51.

FIG. 6 shows the construction of the temperature sensor A. It comprises a hollow metal cylinder 19 serving as one electrode, which is closed at one end and open at the other end and containing water 20, an insulating plug 21 sealing the open end of the cylinder 19, a terminal rod 22 serving as the other electrode, which penetrates the plug and is inserted into the hollow cylinder 19, with an inner portion immersed in the water 20, a terminal 23 attached to the cylinder 19, and an opposite terminal 24 attached to the terminal rod 22. The resistance between the opposite terminals 23 and 24 is small while the water 20 remains in the liquid phase, while it becomes a large value when the water 20 is solidified.

The temperature sensor shown in FIG. 5 is of the construction described above. With a voltage applied between the terminals 23A and 24A current flows between the terminals 23A and 24A when the water 20 remains in the liquid phase, while no current'flows between the terminals 23A and 24A when the water 20 is in the solid phase. This is utilized for the detection of the temperature of 0C, in response to which the cooling operation may be automatically on-off controlled through a cooling operation on-off control circuit connected between these terminals. The voltage applied between these terminals is desirably an a-c voltage from the standpoint of avoiding the electrolytic etching of the temperature and electrolysis of the water in the temperature sensor.

A frost detector E described earlier in connection with FIG. 4 is held free from vibration on a vibrationproof support 52 and faces a cooling fin 49 near the downstream end of the meandering cooling medium pipe 51. Numeral 53 designates a blast fan disposed on the back of the heat exchanger 9.

Connected across theterminals 23 and 24 of the temperature sensor A and across the terminals 47 and 48 of the frost detector E is a defrosting control circuit generally designated at 54. Connected between the terminals 23 and 24 of the temperature sensor A is a series circuit consisting of the primary winding of a transformer 56 and the secondary winding of a power source transformer 55. Connected between the terminals 47 and 48 of the frost detector E is the primary winding of a transformer 57. The secondary windings of the transformers 56 and 57 have one end grounded and the other end connected to the base of respective transistors 58 and 59. Thus, the current flowing in the emittercollector path of the transistors 58 and 59 is controlled with the current flowing respectively between the terminals 23 and 24 and between the terminals 47 and 48. Microrelays 60 and 61 are connected to the respective transistors 58 and 59 so that they may be excited by the current amplified through the respective transistors 60 and 61. The microrelays 60 and 61 are connected through a relay 66 having self-holding circuits 64 and 65 across source terminals 62 and 63. The microrelay 60 is constructed such that its contacts 60x and 60y are in contact with each other in its excited state, while the other microrelay 61 is constructed such that its contacts 61x and 61y are in contact with each other in its non-excited state and get out of contact when it is excited. Numerals 67 and 68 designate a defrosting operation switch provided in the relay 66. When this switch is closed, the solenoid 13a is activated to switch the three-way electromagnetic valve 13 over to the side of the by-path 12, while at the same time the solenoid 11a is activated to close the electromagnetic valve 11. When this state is brought about, the hot gas coming from the heat exchanger 9 for the freezing storage compartment 9 flows through the by-path l4 and expansion valve 15 into the heat exchanger 10 for the cold storage compartment. Further upon closure of the defrosting operation switch the aforementioned heating means 16 is rendered operative, as will be described hereinafter.

In the operation of the defrosting mechanism described above, whenthe water contained in the temperature sensor A remains in the liquid phase in the initial state of the operation of the refrigerator, current flows between the terminals 23 and 24 to cause current flowing into the base of the transistor 58 so as to amplify the current through the emitter-collector path of the transistor 58, thus exciting the microrelay 60 to close the contacts 601: and 60y. Meanwhile, while the aforesaid gap 50 is present between the defrosting detector E and cooling fin 49, the vibrations of the cooling fin 49 are not transmitted to the pick-up 43 in the defrosting detector E. Therefore, no current flows between the terminals 47 and 48, and the microrelay 61 is in the nonexcited state so that the contacts 61x and 61y are in contact with each other. With the contacts 60x and 60y of the microrelay 60 and contacts 61): and 61y of the microrelay 61 both in the close state, the relay 66 having the self-holding circuits 64 and 65 is held in the excited state, so that the defrosting operation switch of contacts 67 and 68 is open. Thus, the threeway electromagnetic valve 13 is open to the side of the main path 2 and the electromagneticvalve 11 is open. In this state, the cooling medium from the compressor 1 flows through condenser 3, expansion valve 4, heat exchanger for the freezing storage compartment, electromagnetic valve 11 and heat exchanger 10 for the cold storage compartment to the main path 2 leading back to the compressor 1.

As the cooling in the freezing storage compartment 7proceeds, the water contained in the temperature sensor A provided on the upstream side of the meandering cooling medium pipe 51 first freezes, thereupon the current between the terminals 23 and 24 vanishes to release the microrelay 60, thus opening the contacts 60x and 60y. However, the self-holding circuit switch of contacts 64 and 65 in the relay 66 remains closed owing to the action of a coil 69, so that the defrosting operation switch of contacts 67 and 68 remains open. Therefore, the defrosting operation isv not started.

As the cooling operation continues for further cooling the inside of the freezing storage compartment, the moisture in the air within the compartment condenses and is attached onto the cooling fin 49 and freezes thereon into frost. The frost formed'in this manner builds up to eventually fill the gap 50 between the defrosting detector E and vibration sensing plate 45. When this situation is reached, the vibration of the cooling fin 49 caused by vibrations due to the operation of the compressor 1, vibrations clue to the passage of the cooling medium in the cooling pipe 1, vibrations due to the rotation of the blast fan 53, etc.,, is transmitted through the aforementioned frost to the pickup 43 to cause current between the terminals 47 and 48, thus causing current to flow into the base of the transistor 59 so as to amplify the current in the emitter-collector path of the transistor 59 for the excitation of the microrelay 61. As a result, the contacts 61x and 61y are opened, thus releasing the relay 66 to close the defrosting operation switch of contacts 67 and 68. Thus, the three-way electromagnetic valve 13 is switched over to the side of the by-pass 12 by the action of the solenoid 13a and at the same time the electromagnetic valve 11 is closed by the action of the solenoid 11a. (The operation of the heating means at this time will be described hereinafter.) In this state, pressurized hot gas is forced out of the compressor 1 and flows through the by-pass 12 into the heat exchanger 9 for the freezing storage compartment. Asthe hot gas flows through the heat exchanger 9, the frost accumulated thereon is melted away. In the above manner, the defrosting is effected. The medium having passed through the heat exchanger 9 for the defrosting is circulated through the by-pass 14 into the expansion valve 15, and the expanded medium I therefrom flows through the heat exchanger 10 for the cold storage compartment and then back to the compressor 1.

As the defrosting proceeds, the frost filling the gap-50 between the cooling fin 49 and the vibration sensing plate 45 is melted to cut the mechanical contact therebetween, whereby the transmission of vibration of the cooling fin49 to the pick-up 43 of the frost detector E is cut. As a result, the amplified current in the emittercollector path of the transistor 59 vanishes, so that the microrelay 61 is released to close its contacts 61x and 61 y. At this time, however, the other microrelay 60 still remains in the excited state so that the self-holding circuit switch contacts 64' and 65 remain out of contact.

Therefore, the relay 66 remains released, thus holding the defrosting operation switch contacts 67 and 68 closed for continued defrosting operation.

The defrosting proceeds toward the upstream end of the cooling medium pipe 51 until the temperature sensor A detects a predetermined temperature, whereupon current is caused to flow between the terminals 23 and 24 to reexcite the microrelay 60, so that the contacts 60x and 60y are closed to activate the relay 66 so as to open the defrosting operation switch contacts 67 and 68. As a result, the defrosting operation is completely stopped, and the circulation of the cooling medium through the main path 2 is resumed. The above sequence is repeated.

The afore-mentioned defrosting effectively proceeds so long as the cooling operation based on the temperature detection on the side of the cold storage compartment 8 continues. During this time, the compressor 1 is operative, so that pressurized hot gas forced out of the compressor 1 flows through the three-way electromagnetic valve 13 into the heat exchanger 9 for the freezing storage compartment for the defrosting opera tion. However, when the cold storage compartment 8 is sufficiently cooled, the cooling operation is stopped as mentioned earlier. Then, the compressor 1 is no longer operative, and the flow of pressurized hot gas into the heat exchanger 9 for the freezing storage compartment ceases. When this state sets in, the speed of I progress of defrosting within the freezing storage compartment 7 is extremely reduced.

According to the invention, the aforementioned heater 16 is operated during thedefrosting operation to provide for continuous cooling operation. More partic ularly, when the defrosting operation switch contacts 67 and 68 are closed, a switch 80 for operating the heater 16 is adapted to be also closed, and upon opening of the defrosting operation switch contacts 67 and 68 the heater operation switch is adapted to be opened. With such circuit construction, during the aforementioned defrosting operation a substantially equal amount of heat to the heat absorbed by the heat exchanger 10 is generated by the heater 16 so that the inside of the cold storage compartment 8 continues to be held under practically optimum temperature condition. Thus, during the defrosting operation the pressurized hot gas always flows into the heat exchanger 9 for the freezing storage compartment, so that the defrosting proceeds promptly. Besides, since with the heater 16 operated in the above manner the temperature inside the cold storage compartment may be held substantially constant, the flood-back to the compressor 1 can be eliminated.

While one preferred embodiment of the invention has been described above, it will be readily understood by one skilled in the art that various changes and modifications in the detailed construction are possible in carrying out the invention. For example, while in the preceding embodiment a pressurized hot gas defrosting system has been used to effect defrosting on the freezing storage compartment side, any well-known defrosting system such as water spray system and electric heater system may be used in addition to the above hot gas system to obtain increased defrosting speed. Also, it will be apparent from the foregoing description that the invention is also applicable where the defrosting is intermittently done by using a timer or manual switch as frost detector means to detect frosting on the freezing storage compartment side. Further, while the resis- FIG. 7 shows another embodiment of the invention applied to the case where a heat exchanger 9 for the freezing storage compartment 7 and a heat exchanger 10 for the cold storage compartment 8 are connected in parallel. In this embodiment, the main path 2 branches into two branch paths 102 and 202. The branch path 102 leads to the heat exchanger 9 for the freezing storage compartment, while the branch path 202 leads to the heat exchanger 10 for the cold storage compartment. The branch paths 102 and 202 after the respective heat exchangers 9 and 10 re-unite into the main path 2. Expansion valves 104 and 204 are provided on the respective branch paths 102 and 202. By appropriately adjusting the throttle. aperture of these expansion valves the inside of the freezing storage compartment 7 may also be held at a desired permanent low temperature, as well as providing for the aforementioned temperature control on the side of the cold storage compartment. For the defrosting medium path, there is provided a by-pass path 112 leading from a three-way electromagnetic valve 13 and terminating in the branch path 102 after the expansion valve 104 and another by-pass path 114 leading from a three-way electromagnetic valve 111 provided on the branch path 102 after the heat exchanger 9 for the freezing storage compartment and terminating in the branch path 202 before the expansion valve 204. During the defrosting operation, pressurized hot gas forced from the compressor l is circulated through three-way electromagnetic valve 13, by-pass 112, branch path 102, heat exchanger 9 for the freezing storage compartment, threeway electromagnetic valve 111, by-pass 114, branch path 202, expansion valve 204, heat exchanger 10 for the cold storage compartment, main path 2 and back to the compressor 1. It will be readily apparent that prompt defrosting in the freezing storage compartment can be obtained in the entirely Same manner as in the previous embodiment.

As has been described in the foregoing, according to the invention in the combination type refrigerator as described in the outset of this specification, use is made of a heating means, which can generate substantially the same amount of heat as the heat absorbed by the heat exchanger for the cold storage compartment, that is, an amount of heat just sufficient to permit continuous operation of the cooler without causing any temperature rise in the cold storage compartment during the defrosting operation in the freezing storage compartment, and which is disposed within the cold storage compartment or in the vicinity of the heat for the cold storage compartment and is operated during the defrosting operation on the side of the freezing storage compartment. Thus, during the defrosting operation the cooling on the side of the cold storage compartment can be such that the inside thereof is held under a practically optimum temperature condition to ensure continuous operation of the cooler. During this time, therefore, pressurized hot gas may always be supplied to the heat exchanger for thefreezing storage compartment to effect prompt and complete defrosting. Furthermore, by the provision of the heating means there is no possibility of excessively lowering the temperature in the cold storage compartment, thus eliminating the occurrence of the so-called flood-back or flowing of the cooling medium after heat exchanger for the cold storage compartment in the liquid phase back to the compressor. Thus, there is no need of providing any particular flood-back preventive means.

What is claimed is:

1. In a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchangers, switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, and means for defrosting said freezing storage compartment by connecting both of said heat exchangers in series with a valve acting as an expansion valve between said heat exchangers and directly supplying pressurized hot gas to the heat exchanger for the freezing storage compartment, the improvement comprisingi heating means provided in said cold storage compartment for generating an amount of heat sufficient to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing storage compartment, and means for operating said heating means only during the defrosting operation in said freezing storage compartment.

2. In a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat ex-.

changer, switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, and means for defrosting said freezing storage compartment by connecting both of said heat exchangers in series with a valve acting as an expansion valve between w compartment during the defrosting operation in said freezing storage compartment, and means for operating said heatingrneans only during the defrosting operation in said freezing storage compartment.

3. A method of defrosting storage compartment of a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchangers, and

switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, comprising, at intervals when the freezing storage department is in need of defrosting:

connecting both of said heat exchangers in series through an expansion valve positioned therebetween, if said heat exchangers are not already so connected; directly supplying pressurized hot gas to the heat exchanger for the freezing compartment; and heatinglsaid cold storage compartment with sufficient heat to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing compartment.

4. A method of defrosting the freezing storage compartment of a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchangers, and switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, comprising, at intervals when the freezing storage department is in need of defrosting:

connecting both of said heat exchangers in series through an expansion valve positioned therebetween, if said heat exchangers are not already so connected, directly supplying pressurized hot gas to the heat exchanger for the freezing compartment; and heating the heat exchanger of said cold storage compartment with sufficient heat to permit continuous operation of said cooling means without causing V any temperature rise in said cold storage compartment during the defrosting operation in said freezing compartment.

l= l l= UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,822,564 Dated July 9, 1974 Kiyoichi NIJO Ihventofls) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

insert therefor -by-passpath-;

i Col. 2, line 61, delete "by-pass-part" and g Col. 4, line 63, after "temperature" insert 5 sensor A Signed and sealed this 8th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents RH PC4050 ($0 69) USCOMM-DC 03764 v.5. covnuunn "nmnc ornct no o-au-un 

1. In a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchangers, switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, and means for defrosting said freezing storage compartment by connecting both of said heat exchangers in series with a valve acting as an expansion valve between said heat exchangers and directly supplying pressurized hot gas to the heat exchanger for the freezing storage compartment, the improvement comprising: heating means provided in said cold storage compartment for generating an amount of heat sufficient to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing storage compartment, and means for operating said heating means only during the defrosting operation in said freezing storage compartment.
 2. In a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchanger, switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, and means for defrosting said freezing storage compartment by connecting both of said heat exchangers in series with a valve acting as an expansion valve between said heat exchangers and directly supplying pressurized hot gas to the heat exchanger for the freezing storage compartment, the improvement comprising: heating means provided in the vicinity of the heat exchanger for said cold storage compartment for generating an amount of heat sufficient to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing storage compartment, and means for operating said heating means only during the defrosting operation in said freezing storage compartment.
 3. A method of defrosting storage compartment of a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means inCluding a compressor for circulating coolant through said heat exchangers, and switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, comprising, at intervals when the freezing storage department is in need of defrosting: connecting both of said heat exchangers in series through an expansion valve positioned therebetween, if said heat exchangers are not already so connected; directly supplying pressurized hot gas to the heat exchanger for the freezing compartment; and heating said cold storage compartment with sufficient heat to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing compartment.
 4. A method of defrosting the freezing storage compartment of a combination type refrigerator having a freezing storage compartment provided with a heat exchanger, a cold storage compartment also provided with a heat exchanger, cooling means including a compressor for circulating coolant through said heat exchangers, and switch means for on-off controlling said cooling means in response to the detection of a predetermined temperature in said cold storage compartment, comprising, at intervals when the freezing storage department is in need of defrosting: connecting both of said heat exchangers in series through an expansion valve positioned therebetween, if said heat exchangers are not already so connected, directly supplying pressurized hot gas to the heat exchanger for the freezing compartment; and heating the heat exchanger of said cold storage compartment with sufficient heat to permit continuous operation of said cooling means without causing any temperature rise in said cold storage compartment during the defrosting operation in said freezing compartment. 